Symptoms That You Should Perform This Procedure

If you're considering doing this, you have a 25+ year old Corvette.
Vibrations, current flow, heat and time conspire to cause internal components
to break down and solder joints to break. This manifests itself in the
following ways:

The four bulbs which illuminate the cluster remain dark, even with the ignition on

When the ignition is on, the cluster remains dark and the info can't be seen

Sometimes, hitting the dash or hitting a bump causes the cluster to start
working properly

While the Digital Cluster is Disassembled

Sunlight causes the LCD polarizing filters to fade, which causes the
information on the cluster to disappear. The LCD panels should appear black
while the cluster is off. If you can see the colored info when the cluster is
off, the polarizing film has faded and should be replaced.
Click Here to buy.

Example of cluster with sun-faded polarizing film

If you're having issues with the cluster being too bright or too dim,
consider replacing the photocell while the cluster is apart.
Click Here to buy.

Example of cluster with defective photocell

Disassembling the Cluster

Some notes on soldering and desoldering

Removing Solder: Use the solder wick to remove the solder which holds the
old components in place. Place the wick over the solder to be removed and heat
the top side of the wick. When it's hot enough, the solder will flow from the
connection to the wick. Use a fresh (copper-colored) piece of wick for each removal.

When soldering, heat the connector lead and the solder pad on the circuit
board (simultaneously). Once these two locations are sufficiently heated, feed
fresh solder into the joint.

Replacing the Board Connectors

Over time, heat, vibration and bad design cause the board connectors or their
solder joints to fail. Not all look as bad as the one in Figure 1, but they
almost always need to be replaced.

Figure 1 - Burned Board Connector

Figure 2 - The bottom board connector before replacement

On the bottom circuit board (the one you took out last), remove the old
connector using a soldering iron and desoldering braid or another desoldering
method of your choice. When the solder has been removed and the connector is
ready to be removed, you should be able to pull it away from the board by
hand. Don't use force to remove the connector, as the hole plating (which
connects top traces to bottom traces) can be damaged! See Figure 2.

Figure 3 - The bottom board connector after removal - bottom of board

Figure 4 - The bottom board connector after removal - top of board

The connector will tend to warp when resoldered, which results in unevenly
spaced pins. You can prevent this by temporarily installing the top board
connector onto the pins of the bottom board connector.

Figure 5 - Reinstalling the bottom board connector

Solder the pins of the new connector to the board.

Figure 6 - The bottom connector after installation - bottom of board

Figure 7 - The bottom connector after installation - top of board

Figure 8 - The top board connector before replacement - bottom side of board

Using a soldering iron and desoldering braid (or a desoldering method of
your choice), remove the old white connector from the top board. When the
solder has been removed and the connector is ready to be removed, you should
be able to pull it away from the board by hand. Don't use force to remove the
connector, as the hole plating (which connects top traces to bottom traces)
can be damaged!

Figure 9 - The top board after removal - top side of board

Figure 10 - Reinstalling the top board connector - bottom side of board

Next, resolder the new connector into place using 60/40 Tin/Lead Rosin Core solder.

Figure 11 - Top Board Connector after installation

Using alcohol and cotton swabs, clean the excess rosin from the connections
and board.

Reworking Other Problem Solder Joints

Desolder and then resolder the joints on the yellow board capacitor shown
in Figure 7

Desolder and then resolder the brown resistor shown in Figure 7

Desolder and then resolder the dimmer transistor (the black thing with
three leads) shown in figure 7

Heat from the factory bulbs causes the riveted connection of the dimmer
transistor to become loose over time. Scrape the sides of the heat sink tab
(opposite end from the three leads) and then solder it to the large heat
sink pad on the bottom board. See Figure 7.

Restoring the LCD Panels

Inspect the polarizing filters on the LCD panels. If you see a fade ring
around the edges, consider
replacing the polarizing filters on the LCD
panels. Now is the time to do that repair.

Figure 12 - Sun-faded film on left, new film on right

Figure 13 - If you can see colored info when the panel is off, the polarizing
film has faded

Follow the detailed instructions to install new polarizing film -
Click Here

Retouching the LCD Paint

If the black paint on the back of the LCD panels has worn through, light will
shine through the panel in areas other than the places it should. Use black
enamel acrylic paint designed for glass and a small paint brush to repaint
that area. Note that we supply the correct paint and a brush if you purchase
our LCD Polarizing Film kit. Be careful
to avoid areas near the factory graphics, and in the areas of the LCD
segments!

Note: Let the paint dry completely before reassembling, or the panel will
stick to the colored diffuser sheet!

Hold the painted panels up to the light to be sure the new paint completely
blocks the light. Retouch if necessary.

The Internal Power Supply

If your cluster displays randomly flickering LCD segments along with
intermittent backlighting, the onboard power supply (Fig 1) may need to be
rebuilt. We sell a kit of parts to replace commonly needed components -
Click Here

The documentation for troubleshooting and rebuilding the internal power supply
is located here

Photocell Dimmer Check

Example of cluster with defective photocell

If your cluster is too dim during the day, or too bright in the evening or
night, it may have a defective photocell. This is a low-cost part, and while
the cluster is apart, it's a great time to replace the photocell.

While the cluster is powered on, hold your hand over the photocell (top left
corner). The cluster should dim noticeably. If not, the photocell may be
defective. Consider replacing it with parts available
here

You can also use a digital multimeter to check the photocell. Measure the
resistance of the photocell (while it's in-circuit is fine). It should measure
<75k Ohms when exposed to room light, and > 1 Megaohm when dark. If it
doesn't, the dimmer functionality won't work properly. Consider replacing it
with parts available here